hat nailer 

an individual who charges excessively for goods or services, often associated with used car dealers in the UK; etimology becomes clear when hat is taken to mean glans penis

You don't want to buy anything from Bracey, he's a well-known hat nailer!

hat nailer by flubbermubber July 7, 2006

Get your hat nailed on 

To get ripped off, screwed over, swindled

You're going to get your hat nailed on when you buy this car.

Get your hat nailed on by ScarboroughPeel December 13, 2017